Do you grow vines or vegetables? Why is it important that the posts are made of wood?
Concrete posts contain fixture pieces of iron to support them. In time, though, the iron pieces rust and as a result the iron ions get into the soil and disturb its optimal pH. This greatly influences the plant growing. The food qualities of the fruit and vegetables change due to the admixture of unnecessary ions from the concrete posts.
Wooden posts are absolutely harmless as they are natural products. Acacia wood are used for their production as they are known for their strength and resistance to environmental conditions. The most important advantage of wooden posts is that they do not affect the taste and quality of the produced vines, vegetables or fruit. Other than that, they are a sign of an environmentally-oriented thinking, typical for the responsible and modern vine- or vegetable-producer.